Improved grinding-platb for paper-pulp engines



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Letters Patent No. 94,816, lated September 14, 1869.

The Schedule referred to in these Letters Patent and making part of the same To all to whom, these presents shall come:

Be it known that I, PHmEAs FROST, of Medfield, in the county of Norfolk, and Common wealth o f Massachusetts, have made an invention of a new and useful Improvement in Grinding-Plates of Paper-Pulp Engines; and do hereby declare the following to be a full, clear, and exact description thereof, due reference being had to the accompanying drawings, makin g part of this specification, and in which- Figure 1`is a perspective view, and

Figure 2, a vert-ical and transverse section of my invention.

The invention herein described, and which constitutes the subject-matter of' this patent, is an improvement in the manufacture of bed-plates, so called, of paper-pulp grinding-engines, this bed, in general, being Acomposed ot' a plurality of long thin plates of steel, laid sideby side, edge uppermost, and bolted together, a bar of iron' or wood being interposed between every two adjacent plates, in order to` create intervening interstices to enable the operation of grndingthe pulp to proceed effectively.

Several modes have been heretofore adopted' in producing bed-plates for pulp-engines, the original one being an alternate series of steel plates-or knives, and of sunken iron bars, bolted together, as before mentioned, the knives being ground to a bevelled edge, in order to produce a cutting-surface to the bed-plate.

The knives of a plate thus made were effective only for a short time, inasmuch as the thickness of their edges increased from the rst moment of service.

Such knives required frequent grinding, and the labor of removing and grinding each knife was a matter of great moment in a large establishment, in addition to which the bed-plate entire must be raised up and bolstered, to compensate for its decreased height, resulting from the wasting away of the knives.

A later mode of constructinga bed-plate was to ernploy, in place of the sunken iron bars, aseries ofwooden bars, disposed flush with the cutting-edges of the knives and wearing away in company with suchY knives, tlie knives in this case being composed of steel plates sufijcientl y thin to present at all times a cutting-edge. It was found in practice that the action of wooden filling was' injurious, inasmuch as, owing to the absence of intervening interstices between the knives, little cutting-edge was obtained.

This'fo'rm of bed-plate was also subject to the same objection as that first mentioned, that .is to say, it must be raised up to compensate for the waste 'of the knives.

This matter of raising and bolstering the bed was one of much time and annoyance, as much diliiculty was experienced in adapting` its cutting-surface to that of' the revolving cylinder above it, and in making it sui`1- cicntly solid.

Still another and later, as well as much more effective manufacture of bed-plate, is that shown and described in Letters Patent of the United Stat-*es issued on the 23d day of May, 1865, to Oliver Morse, of .N eedham Lower Falls, Massachusetts.

This last invention is composed of a series of iron bars, arranged face to face together, and secured by bolts extending laterally through them,intervening spaces being thus created for reception of a series of thin steel plates or bladesof sniiicient width to wear for a considerable length of ltime; the main point soughtand covered in this patent being to produce a series of cutters which should be susceptible of being raised above the edges of the supporting bars as fast as they may become worn.

These plates were of peculiar form, that is, they were provided with a series of slots, through which the confining bolts passed, these slot-s permittingof' the necessary elevation of the plates.

Several important and decided objections have made themselves manifest in the practical use of this patented bed-plate.

' One of the principal of such objections is the fact that as the bolts,"which confine not only the cuttingplates or knives, but the whole bedplate together, must be placed so low downto furnish sufficientmetal above the slots of the former, a general. insecurity or looseness andchatteringof the upper and cuttingedges of the knives ensues.

As the operation of grinding ragsinto paper-pulp is one requiring solid and powerful machinery. This objection last named is one of great concern.

Another objection found to exist to the said patent bed-plate is the necessity of' employing a number of keys or props of various widths, which must be placed under each knife, as itis raised, to compensate for the wear upon it, and the knives being of peculiar charaoter, can be furnished only at a few and given places.

It has been found a matter of time and perplexity in the use of this patented pla-te to adjust its series of knives, after each successive elevation, to the circumf'erence of the roll, which acts in conjunction with it, since it becomes necessary to produce a concave cutting-surface to these knives in aggregate, this concavity corresponding to the periphery of the roll.

Another objection to the Morse plate, which is applicable to all others heretofore in use, is the fact that the general surface of the roll becomes, for some peculiar reason, convex in the direction of `its length, owing to the length of time tl at it is subjected to the action of the knives, without c ange or removal of the latter.

My present in vention consists in first forming a bed, composed of a series of bars, a a, &c., laid atwise, and bolted securely together, its construction enablingthese bolts l) 5, &c., to be placed as near as may be desired to its upper part.

Every alternate bar is of less Width than its neighbor, thus creating shallow spaces for the reception of the cutting-knives c c, 85o., or blades, which till such spaces, it being-observed that the upper edges o f both series of bars are disposed transversely in a concave line, the radius of the circle of' this concavity being equal to that of the roll, which operates upon the bedplate.

In 'this'way, I obtain a cutting-surface which is at all times and without any preparation or labor adaptedv V.produced at small cost, and in this respect obviate one important objection heretofore urged against the patented plate above referred to.

The knives of xnykbed-plate are narrow, in order that the confining-bolts may be brought near to the -upper edge ot' the .bed-plate, which is easily accomplished, as these knives are entirely disposed above such bolts.

Care only should be Laken that the knives possess sutiicient width to receive a firm and unyielding bearing-surface.

thus prevent looseness or chattering incident to the aboveementioned patented roll.

' As soon as one of the narrow knives which I adopt is .worn down to nearthe edge of the bars of the bedplate, I loosen the bolts which coniuethe whole, re'

move such knives andreplace them by new ones, and

subsequently tighten the bolts to make all secure.

As the knives are of uniform Width, the concavlty ot' the cutting or vgrinding-surface ot'the bed-plate is perfect, while the time required to remove the old and insert thevnew knii'e is comparatively insigniiicant.

Another advantage incident to my lnventionwlnch no other of its class possesses is, that, owing to the Claims.

I claim- 1. A bed-plate, so called, for paper-pulp engin es, composed-of two series of upright bars and their movable `knives or blades, when the latter are' placed eutrely abovethe confining-bolts of the device, andwh en the foundation of such knives is a concave surface transversely, essentially in manuel' and for the purpose as explained.

2. The body or `foundation of a bed-plate7 for paperpulp engines, composed of two series of bars, when the4 upper edges of lsuchbars, in aggregate, compose concave surtaces transversely of their length, substantially in manner and for the purpose hereinbefore described and shown.

Witnesses:

FRED. CURTIs, E. GRIFFITH.

PHINEAS FROST. 

